Project III - Molecular Characterization of Liver gene transfer and its oncogenic potential A substantial advantage of AAV for genetic diseases is its ability to confer long-term and high-level transgene expression in liver. This project will evaluate several interesting aspects of molecular biology as it relates to mechanisms of persistence and potential safety considerations. The first specific aim will address the potential for recombination between the transduced vector genome and the latent wild-type AAV that occurs subsequent to a natural infection. The second specific aim will undertake a systematic evaluation of the molecular state and structure of persistent AAV genomes with a focus on the frequency and distribution of integration sites. The final specific aim will undertake experiments to actually quantitate the oncogenic potential of AAV following the delivery to liver. These studies will be performed in a number of murine models including OTCD mice and a model of chronic hepatitis. In addition, the consequence of chronic inflammation on the oncogenic potential of AAV will be studied. Project 3 will rely on Projects 1 and 2 for obtaining tissues from nonhuman primates who have received AAV vectors as part of its goal to undertake molecular characterization. This project will rely on the expertise of Dr. Batshaw in Project 2 to conduct the tumors studies in OTC-deficient mice. Lay description. This project will evaluate the molecular structure of the transferred gene as is resides in the liver cells. Animal studies will be performed to determine if the vector causes tumors.